Disable CGO when running unit-tests

When running unit-tests, go tries to compile using CGO, despite not needing it.
This can lead to errors on systems not having gcc installed, or named wrongly.

Signed-off-by: Jan Schintag <jan.schintag@de.ibm.com>

Makefile

@@ -22,7 +22,7 @@ $(GO):
 
 # Run unit tests
 test: $(GO)
-	$(GO) test ./pkg/... -coverprofile cover.out
+	CGO_ENABLED=0 $(GO) test ./pkg/... -coverprofile cover.out
 
 # Run e2e tests
 functest: $(GO)